On Wed, Feb 08, 2023 at 09:14:53PM +0100, Peter Zijlstra wrote:
> On Wed, Feb 08, 2023 at 07:17:15AM -0800, Dave Hansen wrote:
> > On 2/6/23 04:49, Ard Biesheuvel wrote:
> > > --- a/arch/x86/kernel/apm_32.c
> > > +++ b/arch/x86/kernel/apm_32.c
> > > @@ -609,7 +609,7 @@ static long __apm_bios_call(void *_call)
> > >
> > > apm_irq_save(flags);
> > > firmware_restrict_branch_speculation_start();
> > > - ibt = ibt_save();
> > > + ibt = ibt_save(true);
> >
> > My only nit with these is the bare use of 'true'/'false'. It's
> > impossible to tell at the call-site what the 'true' means. So, if you
> > happen to respin these and see a nice way to remedy this I'd appreciate it.
>
> I've often wished for a named argument extention to C, much like named
> initializers, such that one can write:
>
> ibt_save(.disable = true);
>
> Because the thing you mention is very common with boolean arguments, the
> what gets lost in the argument name and true/false just isn't very
> telling.
>
> But yeah, even if by some miracle all compiler guys were like, YES! and
> implemented it tomorrow, we couldn't use it for a good few years anyway
> :-/
Well... ;)
| [mark@lakrids:~]% cat args.c
| #include <stdbool.h>
| #include <stdio.h>
|
| struct foo_args {
| bool enable;
| unsigned long other;
| };
|
| void __foo(struct foo_args args)
| {
| printf("foo:\n"
| " enable: %s\n"
| " other: 0x%lx\n",
| args.enable ? "YES" : "NO",
| args.other);
| }
|
| #define foo(args...) \
| __foo((struct foo_args) { args })
|
|
| int main(int argc, char *argv[])
| {
| foo(true);
| foo(.enable = true);
| foo(false, .other=0xdead);
| }
| [mark@lakrids:~]% gcc args.c -o args
| [mark@lakrids:~]% ./args
| foo:
| enable: YES
| other: 0x0
| foo:
| enable: YES
| other: 0x0
| foo:
| enable: NO
| other: 0xdead
Mark.
